Hi,
2011/7/28 Tuba Lambanog <tuba.lamba...@gmail.com>
> Hello,
>
> I'm trying to pass a variable through a series of functions, which may
> change the value of the variable. However, the next function in line
> uses the original value, rather than the changed value. Here's a
> pseudo-code of what I'm doing.
>
> (defn process-1 [s]
> ; change value of s then return it
> s)
>
> (def s "something")
> (do
> (process-1 s) ; variable s is changed here
> (process-2 s)) ; process-2 uses the original value of s, not the
> return value from process-1
>
>
beware, "change" in the clojure world means "computing a new value based on
an old one" (as opposed to creating a new value "almost from scratch").
So for example, when you add an element to a map :
(def m1 {:a 1})
(def m2 (assoc m1 :b 2))
you're really creating a new value.
People will sometimes say they "change" m1, but it's not true, it's more to
say that m2 is derived from m1 (sharing most things with m1).
So you need to "pipe" the return value of process-1 into process-2.
The "manual way" to do the pipe :
(let [s-p1 (process-1 s)
s-p2 (process-2 s-p1)]
s-p2)
The "short" way (preferred in your case) :
(-> s process-1 process-2)
HTH,
--
Laurent
> Thanks for the help.
>
> Perhaps a sub-forum for beginners? Kind of embarrassing to ask here
> questions that are so newbie-ish.
>
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